1. Field of the Invention
The present invention relates to an ion-selective electrode that can be incorporated into a monitor for measuring an ion concentration in a sample, such as pH, and a method of producing the same.
2. Description of Related Art
The inventor is aware of various devices for measuring an ion concentration such as pH. Among those devices is an instrument that uses a sheet-type electrode with a flat measuring portion. In the manufacture of this device, the ion-selective electrode is formed with a polyethylene terephthalate (PET) film that is adhered to the glass with one of a family of silicone adhesives. Cross-sections of such structures are disclosed in FIGS. 6(A) and 6(B). As shown in FIG. 6(A), the ion-responsive glass 64 is coated with a layer of a silicone adhesive 63, and then with an overlayer of a primer 62 for adhering the plastic PET film 61.
The embodiment shown in FIG. 6(B) has the PET film 61 covered with a layer of a polyester anchor coating agent 65 and, subsequently, a layer of a polyester family hot melt adhesive 66. This structure is then treated with a silicone family primer 67. Finally, a single liquid dealcoholization-type silicone room temperature vulcanizing adhesive 68 is utilized to adhere the silicone family primer 67 to the ion-responsive glass 64.
Ion-selective electrodes having the above construction frequently have problems in durability. When such electrodes are used in an environment of high temperature and humidity, or in an environment of water of a high temperature, a problem occurs in that the ion-responsive glass 64 is liable to be separated from the PET film 61, and electric installation is frequently deteriorated, reducing the reliability of such an ion-selective electrode.
Thus, there is still a demand for an improvement in providing an ion-selective electrode for measuring instruments.